[Sync EN] intltz_get_iana_id: Add documentation (PHP 8.4) (#5353)

[github-actions]

Commit: https://github.com/php/doc-en/commit/3f1722ae51abab1a1ee5fde3ada01fe5cbb87f36
PR: https://github.com/php/doc-en/pull/5353

Neue EN-Dateien (noch nicht übersetzt)

• reference/intl/intltimezone/getianaid.xml